Hybrid hope or hype?

[AptosDriver]

Found this Cnet review of the Hyundai Sonata hybrid, which shares its powertrain with the Kia hybrid. In a nutshell, the review claims the Hyundai/Kia hybrids' "parallel" system provides superior highway MPG because it enables the cars to run at up to 75 mph on their electric motors. The engineering sounds impressive to me, but what do I know? I'd like to hear, objectively, from folks who do know. Hyundai/Kia are touting their lithium-polymer battery technology and I've seen the critiques of those batteries here. (And also the explanation of the planetary gear at the heart of the FFH's CVT.) But apparently the key to the better highway MPG, per Hyundai/Kia is ultimately the way the electric motor is connected to the wheels:

 

The challenge, says Mark Guin, Hyundai senior development engineer at the Hyundai-Kia America Technical Center in Chino, Calif., was to "come up with our own hybrid system while working around existing patents." Says Guin: "We believe that the solution we came up with is elegantly simple."

 

Hyundai's solution replaces a typical hybrid's transmission-motor assembly with a standard automatic transaxle modified to work with what Hyundai calls a transmission-mounted electrical device. The TMED includes two main parts: a powerful electric drive motor and a solenoid-activated clutch pack. These parts fit in about the same space as a traditional torque converter.

 

"The fine control we can exert over the wet clutch pack makes it possible for us to use a conventional automatic transmission without a torque converter," a notorious energy drain, Guin says.

 

"The TMED enables our 40 mpg highway mileage and high-speed EV operation. Because the torque from the motor runs through all of the transmission's six gears, we can keep the motor running at its optimal rpm," Guin says. Electric motors are more efficient running at lower speeds.

 

The clutching system enables the gearbox to receive power from the 30-kilowatt (40.8-hp) electric motor, the 166-hp 2.4-liter Atkinson cycle four-cylinder gasoline engine, or both.

 

So is this solution "elegantly simple," as the man says, or inelegantly complex? This layman's inquiring mind would like to know more.

[mort]

Hi AptosDriver.

I'd say it's elegantly too simple. The first thing that hit me is how home-brew it all sounds. I bet over at ecomodder.com you can find somebody that wants to replace their torque convertor with a big electric motor...

In the Hyundai the traction motor only charges the traction battery during braking or engine powered driving. When the internal combustion engine (ICE) is disconnected from the transmission it is disconnected from the traction motor too. So Hyundai has a belt driven generator running off the ICE to help recharge the battery when the ICE is not powering the wheels. It seems like there could be times when the traction motor is moving the car, maybe in stop and go traffic, and the ICE is charging the battery through its generator, rather that actually moving the car. Also, estimated mpg for the city cycle is lower than for highway must mean that Hyundai doesn't have regeneration really worked out yet.

 

-mort

[rfruth]

While working around existing patents Hyundai uses TMED and a BAS system - sounds good to me but not "simple"

 

[lolder]

They're flat out wrong ! In a non-plug in hybrid, all the energy comes from fuel. It is ALWAYS, at highway speeds above about 40 mph, more efficient to drive the wheels with a direct gear from the ICE ( Chevy Volt people learned ) than turn a generator, charge a battery, discharge a battery and run an electric motor. It doesn't matter what speed the motor is turning to drive the wheels through the transmission. You can design a motor to run at any speed you want. The electrical losses will ALWAYS be more than direct gearing. The fact that Hyundai even says this makes me worry about their competence to design complex vehicles. If they're getting better highway mpg it's because they are loading the ICE up even more at a slightly lower rpm, they have a lower drag co-efficient Cd and they have a slightly lower weight.

[VonoreTn]

Getting rid of the torque converter is good, but that gets you up to standard transmission FE, not enough. Running at a steady speed with full electric motors is not a great thing in itself either, as many here have tried to explain, electric motor operation, supported by the ICE charging the battery, to run the motors, is actually less efficient than direct drive of the ICE. The efficiency comes with the combination of electric with ICE, so you can use a less powerful ICE supplemented in those rare events of acceleration with the electric motors, and filling in the ICE idle and low load conditions with the electric. Then there is all the fine tuning of the strategy, to charge at just the right time to keep the ICE loaded to reduce pumping losses, and at the right most efficient ICE rpm. It remains to be seen if the Hyundai has done anything better long term than the Prius, and FFH. I'll wait for some objective testing with production level hardware.

 

But I am pleased that we are getting some serious competition for FE improvements, for years all we had was BS about 80 mpg carburetors, and lately, cars that generate hydrogen on the fly, which is a total scam. Maybe we will even get an FE cable channel and some FE magazines, like hot rods have enjoyed for decades. Maybe I'm just getting old but FE is much more exciting to me now than HP.

[AptosDriver]

Well after reading all these replies, which I have to admit I can't entirely follow as my eyes start to glaze over, I'm inclined to think that the Hyundai/Kia solution is too complicated, by half. And in any case, I think that the key wording in the quoted article excerpt is the Hyundai spokesman's own acknowledgment that they were pressed to "come up with our own hybrid system while working around existing patents." As I recall, someone already speculated in a related thread that Hyundai was probably facing patent issues. They probably didn't have any patents that any other hybrid makers wanted to cross license with them (as Ford and Toyota did) and I assume that they wanted to avoid paying licensing fees. If that's what was really driving their hybrid development, then it's possible that corporate financial considerations triumphed over function. The answer to that question will have to wait until the Hyundai Sonata/Kia Optima hybrid rubber meets the road. :shift: